[CAD-1824] List of delisted Stake pools.

[ksaric]

https://jira.iohk.io/browse/CAD-1824

Testing can be done like this.
If there are no delisted pools, the returning list should be empty:

curl --verbose --header "Content-Type: application/json" localhost:3100/api/v1/delisted

[]

You need to delist the existing poolId (or several if you want to see several):

curl --user ksaric:cirask --verbose --header "Content-Type: application/json" --request PATCH --data '{"poolId":"fc80a2a814338475c737df5d1c50253046c8c04eb3663336af7beb38"}' http://localhost:3100/api/v1/delist

curl --user ksaric:cirask --verbose --header "Content-Type: application/json" --request PATCH --data '{"poolId":"cbf68681bbd1758480391706a9717fad6cecd668d3903552364a5d9f"}' http://localhost:3100/api/v1/delist

curl --user ksaric:cirask --verbose --header "Content-Type: application/json" --request PATCH --data '{"poolId":"8517fa7042cb9494818861c53c87780b4975c0bd402e3ed85168aa66"}' http://localhost:3100/api/v1/delist

Then the resulting GET should get you all the poolId that you delisted:

curl --verbose --header "Content-Type: application/json" localhost:3100/api/v1/delisted

[{"poolId":"fc80a2a814338475c737df5d1c50253046c8c04eb3663336af7beb38"},{"poolId":"cbf68681bbd1758480391706a9717fad6cecd668d3903552364a5d9f"},{"poolId":"8517fa7042cb9494818861c53c87780b4975c0bd402e3ed85168aa66"}]